camsmons
Member
Last Activity: 04-19-2024, 03:02 AM
Joined: 09-26-2023
Location: Sydney
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I think I did a bad job when changing the USB-C port, several tiny components are missing from the board - those red circles. and one is misplaced - yellow circle. are they critical for PD?...
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For D12501, my understanding is at least one reading should be similar to the normal reading around 0.5v, as other diodes around. 2 readings both >1v sounds not right. Am I correct?
Just want to make sure before removing it to avoid making more troubles.Leave a comment:
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checked D12501, reading starts from around 0.9v and stop around1.116v, reverse red and black prob, the reading is around 1.673v. does this mean this diode is bad?...Leave a comment:
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found it, [url]https://italchemy.wordpress.com/2021/05/26/update-bios-on-lenovo-laptops-without-battery/[/url]https://found it, [url]https://italc...battery/[/url]...Leave a comment:
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check D12501, reading starts from around 0.9v and stop around1.116v, reverse red and black prob, the reading is around 1.673v. does this mean this diode is bad?Leave a comment:
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had some progress. flashed the latest official BIOS, power adapter still remains at 5V, but can charge the battery slowly around 15W when the laptop is on. it shows the battery is charging, when the laptop is on, it used more power than what's charging. so battery level goes down slowly. only when the laptop is off, battery gets charged actually and slowly.Leave a comment:
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without power adapter, laptop only runs on battery, how can I flash BIOS? downloaded bios update from official website, but couldn't flash it. it ask for AC power connection. anyone please help. thanks....Leave a comment:
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official power adapter has no issue, works for another laptop. also tried another official power adapter from another laptop, same result.
for sure 20v is not selected. there is only 5v from the usb c port.
the PD controller RTS5455 is the original one. at the beginning the charging issue should be only the usb C port which is damaged I believe, seems connectivity issue - had good or bad contact when the plug is pressed or bent. replaced the sub c port - did it twice due soldering skill😅.
now the connectivity seems all good. connections from all VBUS...Leave a comment:
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if flip the power adapter cable, CC1/CC2 voltages also flip from 0.004v/1.661v to 1.661v/0.004v.
The laptop works with the battery. could the issue be a mosfet for PD? Not sure how to check it....Leave a comment:
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tried to use official BIOS update, not allowed since AC power is not connected.Leave a comment:
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the battery is flat currently. I'm considering to charge it separately, then power the laptop with the battery to flash the BIOS I downloaded from here, to see if it make any difference.Leave a comment:
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I don't have a USB type C meter yet. Looking to buy one currently. I have this tester
Plugged in it to the USB C port. in diode mode, readings for CC1 and CC2 pin of this tester are all 0.599V.
Checked voltage of pin 9/CC1 and pin 11 /CC2 of RTS5455 when plugging power to USB C port, voltages are 0.004V and 1.661 V....Leave a comment:
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thanks for that. read that before. how do I know it's this RTS5455 has issue? I checked pin 26 which has 3.3V. does this mean it's good?...Leave a comment:
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Lenovo Thinkpad E15 - FE4A0/FE5A0 NM-C421 REV 1.0 USB C no charging
Need help to fix my son's laptop.
I changed the USB C port, still no charging. checked U5901/RTS5455, pin 25 has 5V, pin 26 has 3.3V. Not sure where to check next.
If any one can tell where I should check next, it'll be much appreciated. Thanks. -
I want to learn something so I can fix things broken.Leave a comment:
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